1. Field of the Invention
The invention relates to a battery module, a method for managing supply of electrical power by a battery module, and a power supply device having the battery module, and more particularly to a battery module, a method for managing supply of electrical power by a battery module, and a power supply device having the battery module that may properly control a number of battery units of the battery module that supply electrical power according to a current required by the load.
2. Description of the Related Art
Many electrical machines used in everyday life, such as televisions, computers, printers, mobile phones, gaming machines, portable audio players, etc., operate with direct current (DC) power. A DC power supply system is important for an electronic device since it provides stable supply or portability of DC power, such that application of the electronic device is not limited due to lack of power.
For example, a UPS (uninterruptible power supply) system is configured to serve as a temporary and emergency power supply when a power source of a computer is abnormally interrupted or unstable, so that the computer may not suffer from data loss or system damage due to abnormal supply of electrical power. Referring to FIG. 1, a conventional UPS device 1 includes a voltage distribution unit 11 that converts electrical power from a three-phase alternating-current (AC) power source 100 to single-phase AC electrical power, and a power supply unit 12 that converts the single-phase AC electrical power provided by the voltage distribution unit 11 to DC electrical power. The DC electrical power is provided to a load, such as a server 200, and to a charging circuit 13 that converts the DC electrical power to a voltage rating of a battery 14 for charging the battery 14. The battery 14 is coupled to a transformer module 15. A switch 16 is coupled between the transformer module 15 and the server 200 and is controlled by the power supply unit 12. When the AC power source 100 stops output of electrical power, the power supply unit 12 controls the switch 16 to make electrical connection between the transformer module 15 and the server 200, so that the battery 14 outputs electrical power that is subsequently converted by the transformer module 15 to DC electrical power required by the server 200. The converted DC electrical power is then provided to the server 200 through the switch 16, thus achieving uninterrupted power supply.
However, the conventional UPS device 1 is only suitable for a single load. In addition to requirement of the voltage distribution unit 11 for converting AC power into DC power, the transformer module 15 of the conventional UPS device 1 is usually implemented using a switching DC-DC converter, which is relatively complicated and has a relatively large size, making it difficult to reduce the size of the UPS device 1, and thus disfavoring application to electronic products that tend to have a light weight and a small size.